Cutter for removing tissue

ABSTRACT

The invention relates to a cutter for removing tissue, with a cutter head, with a cutter shank which carries the cutter head and to which the cutter head is connected in a rotationally fixed manner, and with a drive driving the cutter shank. For the adjustability of the effectiveness of the cutter with the removal of cartilaginous or bony tissue parts there is provided a first rotatable sleeve which comprises an inner bore which is arranged eccentrically to the middle axis of this sleeve, and a second stationary sleeve which is arranged in the inner bore of the first sleeve and which for the passage of the cutter shank comprises an inner bore which is arranged eccentrically to the middle axis of the second sleeve.

BACKGROUND OF THE INVENTION

[0001] The invention relates to a cutter for removing tissue, with a cutter head, with a cutter shank which carries the cutter head and to which the cutter head is connected in a rotationally fixed manner, and with a drive driving the cutter shank.

[0002] Cutters of the previously known type are known in surgery. They are used in order to remove bony or cartilaginous tissue. With this the cutter head may be arranged eccentric to the cutter shank. With this it is achieved that the cutter head with each revolution projects radially outwards over a defined angular path beyond a stationary sleeve or a stationary shank and may remove tissue.

[0003] With such cutters there however arises an unbalanced mass which is not insignificant and which impedes the machining accuracy. Furthermore the effective active regions of the cutter are very difficult to determine accurately so that inasmuch as this is concerned the accuracy of the tissue removal is limited.

BRIEF SUMMARY OF THE INVENTION

[0004] It is therefore the object of the invention to develop further a cutter of the initially mentioned type such that the safety and the accuracy with its use is increased and the tissue removal may be effected with an increased precision. Furthermore the efficiency of the removal is to be increased and the working range - exactly adjustable - is to be increased.

[0005] For achieving this object the cutter according to the invention is characterised by a first rotatable sleeve which comprises an inner bore which is arranged eccentrically to the middle axis of this sleeve, and by a second stationary sleeve which is arranged in the inner bore of the first sleeve and which for the passage of the cutter shank comprises an inner bore which is arranged eccentrically to the middle axis of the second sleeve.

[0006] The arrangement of two sleeves with in each case an eccentric bore for the radial mounting of the cutter shank is achieved in a simple manner in that by rotation of the two sleeves relative to one another the cutter head with respect to its radial projection beyond the outer circumference of the outer sleeve may be adjusted simply and continuously in an exact manner. The effective effect of the cutter head with the removal of tissue may thus be exactly adjusted.

[0007] The handling of the cutter is simplified in that the second sleeve is connected to the drive or its housing in a rotationally fixed manner. Furthermore the first sleeve is preferably connected in a rotationally fixed manner to a rotatable handle; with the latter the effective eccentricity of the cutter head may be simply adjusted.

[0008] Furthermore the eccentricity of the inner bore of the first sleeve and the eccentricity of the inner bore of the second sleeve are equally large. With this it is achieved that by way of a suitable rotation of the two sleeves to one another or of the first sleeve relative to the second stationary sleeve the eccentric projection of the cutter head may be adjusted from zero up to a maximum value.

[0009] Preferably the second sleeve with its outer diameter is arranged in the inner bore of the first sleeve with a clearance fit. Furthermore between the outer diameter of the second sleeve and the inner bore of the first sleeve there may be arranged a sliding bearing or this region may be designed as a sliding bearing.

[0010] With regard to manufacturing and assembly technology there results a simple embodiment when the cutter head and the cutter shank are formed as one piece. Furthermore the cutter shank may be connected to the drive shaft by way of a positive-fit connection. Finally the cutter shank may be connected to the drive shaft further by way of a snap connection.

[0011] For reducing the weight of the cutter the first and/or the second sleeve is essentially designed as a solid component only in the region neighbouring the cutter head, and in the region neighbouring the drive as a hollow component.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the drawing there is shown one embodiment example of the invention which is described hereinafter. There are shown in

[0013]FIG. 1 the cutter without an adjusted eccentricity and

[0014]FIG. 2 the cutter with an adjusted maximal eccentricity of the cutter head with respect to the outer sleeve.

DETAILED DESCRIPTION OF THE INVENTION

[0015] In FIG. 1 there may be seen a cutter 1 which comprises a drive 4 which via a cutter shank 3 drives the cutter head 2. The cutter shank 3 is guided in a system of two sleeves 5 and 8. The first sleeve 5 with this comprises an inner bore 6 in which the second sleeve 8 is accommodated. The second sleeve 8 has in turn an inner bore 9 which serves the passage and the mounting of the cutter shank 3.

[0016] The first sleeve 5 as well as the second sleeve 8 carry their respective inner bores 6 and 9 eccentrically, that is to say the bore axes are not identical to the middle axis 7 and 10 of the sleeves 5 and 8 respectively. In FIG. 2 it is to be recognised that the inner bore 6 is incorporated in the inner sleeve 5 with the eccentricity e₁, whilst the second sleeve 8 carries its inner bore 9 with the eccentricity e₂.

[0017] In the position of the two sleeves 5 and 8 to one another represented in FIG. 2 there thus results as a total eccentricity of the axis of the cutter head 2 or cutter shank 3 with respect to the middle axis 7 of the first sleeve 5 a value of e=e₁+e₂.

[0018] In contrast to this in FIG. 1 the first sleeve 5 is rotated or adjusted relative to the second sleeve such that there results no eccentricty of the cutter head 2 relative to the middle axis 7 of the first sleeve 7. This is achieved in that both eccentricities e₁, e₂ are equally large, the sleeves 5 and 8 however are rotated to one another such that both eccentricities are lifted and the middle axis of the cutter shank 3 is identical to the middle axis 7 of the first sleeve 5. Thus there results no eccentric running of the cutter head 2 relative to the first sleeve 5.

[0019] By rotating the handle 11 which is connected to the first sleeve 5 in a rotationally fixed manner, then there may be infinitely adjusted an eccentricity between zero and e, by which means the cutter 1 may be adapted to the respective working conditions.

[0020] The cutter 1 is preferably suitable for removing cartilaginous or bony tissue in the region of the vertebral column. This is particularly the case for the endoscopic application of the cutter. For this it is the case especially of an exact removal. There is present a running with a balanced mass, and the adjusting of the necessary working eccentricity or working depth may be effected infinitely, exactly and in a simple way and manner. 

1. A cutter for removing tissue, with a cutter head, with a cutter shank which carries the cutter head and to which the cutter head is connected in a rotationally fixed manner, and with a drive driving the cutter shank, characterised by a first rotatable sleeve which comprises an inner bore which is arranged eccentrically (e₁) to the middle axis of this sleeve, and by a second stationary sleeve which is arranged in the inner bore of the first sleeve and which for the passage of the cutter shank comprises an inner bore which is arranged eccentrically (e₂) to the middle axis of the second sleeve.
 2. A cutter according to claim 1, wherein the second sleeve is connected to the housing of the drive in a rotationally fixed manner.
 3. A cutter according to claim 1 or 2, wherein the first sleeve is rigidly connected to a rotatable handle.
 4. A cutter according to one of the claims 1 to 3, wherein the eccentricity e₁ of the inner bore of the first sleeve and the eccentricity e₂ of the inner bore of the second sleeve are equally large.
 5. A cutter according to one of the claims 1 to 4, wherein the second sleeve with its outer diameter is arranged with a clearance fit in the inner bore of the first sleeve.
 6. A cutter according to one of the claims 1 to 5, wherein between the outer diameter of the second sleeve and the inner bore of the first sleeve there is provided a sliding bearing.
 7. A cutter according to one of the claims 1 to 6, wherein the cutter head and the cutter shank are formed as one piece.
 8. A cutter according to one of the claims 1 to 7, wherein the cutter shank is connected to the shaft of the drive by way of a positive-fit connection.
 9. A cutter according to one of the claims 1 to 8, wherein the cutter shank is connected to the shaft of the drive by way of a snap connection.
 10. A cutter according to one of the claims 1 to 9, wherein the first sleeve and the second sleeve essentially are formed as a solid component only in the region neighbouring the cutter head and in the region neighbouring the drive as a hollow component. 